TN570B/C

The TN570 Expansion Interface (EI) is used in R7si/r or later systems. This circuit pack is an interface between the TDM bus and packet bus, and fiber optic links interconnecting cabinets. It is used in a Port Network (PN) between a PN and another PN in a direct-connect system, and between a PN and an SNI in a switch node carrier in a CSS-connected system.

The TN570 provides control channel applications and time-slot interchanging between the PPN and EPNs. It is used when ISDN-BRI and/or ASAI is connected in an EPN, and is always used in R7r or later.

The TN570 carries circuit-switched data, packet-switched data, network control, timing control, and DS1 control. This circuit pack also communicates with the TN775B maintenance circuit pack in an EPN to send the EPN environmental and alarm status to the SPE.

The TN570 is replaced by the TN2305 or TN2306 when an ATM switch replaces the Center Stage Switch.

TN570C circuit packs are used in SREPN (Survivable Remote Expansion Port Network), R7 or later si.